Hydraulic brake system



Dec. 1, 1936. R. c. sABlNs HYDRAULIC BRAKE SYSTEM Filed Feb. 28, 1935 /ven/or 3y hzLsAZZo-rn/eys Patented Dec. l,` 1936 UNITED STATES PATENT ori-lcs Application February 28, 1935, Serial No. 8,681

:i claims.

My invention relates to automobile hydraulic brake operating systems and particularlyV to means for sectionalizing such systems to prevent a. leak in one portion thereof 4from rendering the entire system inoperative. V

In the usual hydraulic brake system a pedal operated pressure pump or master cylinder forces fluid through a system of tubes to the operating cylinders of the several brakes so as to `hydraulically transmit pressure from the brake pedal to the brake shoes. In such a system a leak in any part of the system will prevent the building up of pressure in any part of the system and hence will render the entire system inoperative. Such a possibility creates considerable potential hazard and accordingly is highly undesirable.

A general object of my invention is toprovide a hydraulic brake operating system wherein a leak in one portion of the system will not render the entire system inoperative.

A more specific object is to provide a hydrauiic brake operating system wherein the respective bodies of fluid in several portions of the system are isolated from each other but wherein displacement of fluid in the portion including the master cylinder will cause displacement of fluid in each of the other portions of the system.

Another object is to provide such a system wherein the bodies of fluid in the portion of the system including the pressure pump and the respective portions serving respective ones of the brake actuating cylinders are all isolated from each other and displacement of fluid in the first mentioned portion will cause displacement in each of the remaining portions within predetermined limits.

A further object is to provide a device in such a system for preventing flow of fluid between respective ones of two bodies of fluid both in communication with said device and yet permitting displacement of the fluid of one body to produce a similar displacement of the fluid of the other body.

These and other objects and advantages of the invention will be more fully set forth in the following description made in connection with the accompanying drawing, in which like reference characters refer to similar parts throughout the several views, and in which:-

Fig. vl is a top view of an automobile chassis in dotted lines with my system shown therein in full lines;

Fig. 2 is a vertical sectional' view yof the fluid sectionali'zing device of my system;`

Fig. 3 is a top view of the master cylinders and manifold of my system, and Fig. 4 is a vertical sectional view of another form of my fluid sectionalizing device.`

Referring to the drawing, my hydraulic' brake operating system is shown as applied to an automobile chassis shown in dotted lines in Fig. 1 and including a frame 6, front and rear axles 1 and 8, and wheels 9, all of conventional construction, each of the wheels 9 being equipped with brake drums, brake shoes and hydraulic brake operating cylinder and pistons, all of conventional form and not shown. Clutch and brake pedals I0 and II of conventional designare provided.

Whereas only one master cylinder or pressure applying means is customarily used in a hydraulic brake operating system, I employ a pair of such-master cylinders I2 suitably mounted in parallel relation to each other forwardly of the brake pedal II as shown. The pistonrods I2a of the respective master cylinders I2 are connected to lugs I3a on a yoke I3 by means oi' pins I4 or other suitable means and lugs I3b on the opposite side of the yoke I3 arey connected to the arm Ila of the brake pedal II by means of a nutted bolt I5 or 'other suitable means so that forward movement of thebrake pedal II will cause forward movement of the pis.- ton rods I2a to bring about compressive action within both of the cylinders I2.

A chamber or manifold I 6 is provided to connect the respective outlets of the two master cylinders I2 together and to the respective conduitsor tubes leading to the cylinders of the individual brake actuating mechanisms of the respective wheels 9. 1The outlet of each of the master`l cylinders I2 is connected to the mani- ;fold I6 through a fluid sectionalizing device B to be described in detail. Other similar sectionalizing devices B are provided to connect the marilfold I6 to the respective ones of tubes I1 running to the cylinders of the respective individual brake actuating mechanisms.

Referring particularlyto Fig. 2,: each of the fluid sectionalizing devices B includes a circular base plate I8 and a dome-shaped body I9 having an annularv flange I9a suited for attachment to the annular marginal portion of the plate I8 so that a chamber 20 may beV formed between the plate I8 and the body I9. The outer sides of the plate I8 and the body I9 are respectively provided with externally screw-threaded bosses Ita constitute connection elements by means of which y the iiuid sectionalizing device B is connected to other portions of the brake operating system. The connection elements 9a and I 9b are intended for connection respectively to a source of fluid under pressure and to portions of a brake operating system utilizing fluid under pressure.

The chamber 2li is provided with an elemen dividing the chamber into two portions between which uid cannot flow, this element being deflectible within certain limits to permit simultaneous increase in the volume of one of the two portions of the chamber and corresponding decrease in the volume of the other of the two portions. 'I'he deectible element referred to consists of a diaphragm 2| formed of relatively ilexible and elastic material such as rubber. The annular marginal yportion of the diaphragm 2| is disposed against the inner side of the annular marginal portion of the plate I8 and the normal or non-deflected position of the diaphragm 2| is immediately adjacent and parallel to the inner side of the plate I8 as shown.

A dome-shaped wall or backing element 22 for limiting deflection of the'diaphragm 2| is placed within the chamber 20 in slightly spaced parallel relation to the inner sideof the body I9. The peripheral portion of the wall 22 is provided with an annular flange 22a disposed between the flange |9a of the body I9 and the annular marginal portion of the diaphragm 2|. The annular marginal portions of the plate I8 and diaphragm 2| and the flanges 22a and |9a of the wall 22 and body I9 are'all clamped together in sealed relation by means of screws 23 which extend through suitable apertures in the plate I8, diaphragm 2| and flange 22a and are screw-threadedly engaged in suitable internally screw-threaded apertures in the flange |9a of the body I9. The domeshaped wall is provided with a pluralityv of small spaced perforations or apertures 22h distributed throughout its area for permitting the flow of fluid from one side to the other of the wall 22. The space between the wall 22 and the body I9 serves as a passage between the various apertures 22h and the aperture I 9c of the connection element |9b.

When fluid under pressure is introduced into the fluid sectionalizing device B through the conn ection element I8a this fluid forces deflection of the diaphragm 2| toward the perforated wall 22 and occupies the portion of the chamber 2|l` between the plate I8 and the diaphragm 2|. Any fluid occupying the portion of the chamber 2li between the diaphragm 2| and the body I9 is placed under pressure and is displaced through the apertures 22b of the wall 22 and the connection element I9b. Thus, while no actual flow of uid through the device B can take place, pres,- sure applied to a body of fluid on the left side of the diaphragm 2|, as viewed in Fig. 2, is transmitted to a body .of fluid on the right side of the diaphragm. Due to pressure applied to the first body of fluid, displacement of both bodies offluid will take place and when the back-pressure in the last mentioned body of fluid has become equal to the pressure applied to the first mentioned body of fluid, such displacement of :duid will cease and the diaphragm 2| will become stationary in a position intermediate between the plate I8 and the perforated wall 22. If little or no back-pressure is built up the diaphragm 2| will continue to denect until it bears against the perforated wall or backing element 22 whereafter no further dlaplacement of the fluid at the left oi the diaphragm can take place. The perforated wall 22 then serves as a backing plate for bracing the diaphragm 2| against the pressure imposed upon the diaphragm 2 I by the fluid at the left thereof and thus prevents rupturing of the diaphragm 2|. Under normal conditions when the diaphragm 2| deflect:

.only to a position intermediate of the plate Il and the perforated wall 22, the back pressure on one side of the diaphragm equals the applied preasure on the other side and hence the diaphragm is under no stress tending to rupture the same.

A' plurality of the above described fluid sectionalizing devices B are connected in my hydraulic brake operating system as follows. The connection elements Ita of a pair of devices B are connected to the respective outlets of the two master cylinders I2 and theconnection elements Iilb of these devices B are both connected to the manifold I6. vWhere four individual wheel brake operating mechanisms are to be operated, as in the illustrated embodiment of the invention, the connection elements Ita of four devices B are all connected to the manifold I6 and the connection elements I9b of these four devices Bare respectivelyv connected to four tubes I'I each of which runs to one of the four individual brake operating mechanisms. From the above it should be apparent that my system contains a number of separate bodies of fluid between which there can be no flow of fluid but between which pressure can be transmitted from the master cylinders |2 toward the individual brake operating mechanisms. The respective ones of these bodies of fluid are separated from each other by the diaphragms 2| of the devices Band are located in the respective ones of the master cylinders |2, in the manifold I6 and in the respective ones of the tubes I'I and associated individual brake operating mechanisms.

When the brake pedal |I is pressed, the bodies of fluid in the two master cylinders I2 are placed under pressure and this pressure is transmitted to the body of fluid in the manifold I6 through the deilectible diaphragms 2| of the devices B which connect the respective master cylinders I2 to the manifold I6. The pressure on the fluid in the manifold I6 is transmitted to the bodies oi fluid in the respective tubes I1 through the diaphragms 2|y of the devices B which connect the manifold I 6 to the respective tubes I1. The fluid in each tube I1 is, of course, in direct communication with the fluid in the cylinder of one of the individual brake operating mechanisms and hence development of pressure inthe respective tubes I1 causes application of the respective individual wheel brakes.

'I'he proportions of the devices B should be such that maximum braking effect can be secured when the diaphragm 2| is still some distance away from the perforated wall or backingplate 22.

Should a leak occur in either of the master cylinders I2 pressure developed in the other one of the cylinders I2 cannot drive fluid back from the manifold I6 into the faulty cylinder I2 and hence this pressure is available for operating the brake system. 'I'he diaphragm 2| of the device B between the faulty cylinder and the manifold I6 will block back flow of fluid into the faulty cylinder I2 and-the diaphragm 2| since it is in its normal'position lying against the plate I3, will be restrained by the plate I8 against either deection or rupture.

Should the cylinder of' one of the individual brake operating mechanisms or the tube I1 serving the same become leaky, pressure in the manifold I G produced by the initial part of a brake applying operation of the master cylinders I2 will force the diaphragm 2I of the device B to which that tube I1 is connected against the perforated backing element of that device B whereupon further deflection of the diaphragm 2I and further displacement of fluid toward the leak will be halted. Since the leak prevents, or at least seriously limits, the building up of back pressure in the tube I1 it should be obvious that l only a small part of normal brake operating pressure is required in the manifold I6 to cause the above described action of the diaphragm 2|. Continuation of the brake applying operation of the master cylinders I2 will obviously build up pressure in the manifold I6 and all of the tubes I1 and individual brake operating cylinders except the leaky one. Consequently three ofthe four brakes will be applied even though a leak has occurred in the portion of the system serving one of the brakes.

It should be obvious that the automatic brake equalizing characteristic inherent in conventional hydraulic brake operating systems is also inherent in my hydraulic brake operating system.

As in conventional hydraulic brake operating systems, air bleeder plugs 24 and fluid replenish- `ing reservoirs 25 of conventional design are placed at suitable points in my system. `An air bleeder plug 24 is screwed into a suitable internally screw-threaded apertured portion of the upper part of the plate I8 of each of the devices. A fluid replenishing reservoir 25, having a suitable connection stem 25a, is mounted on each device B by means of the screw-threaded lower end of the stem 25a which is engaged in an internally screw-threaded apertured portionof the upper part of the body I9. In an enlarged porvided to permit downward flow of fluid from the reservoir 25 when no pressure exists in the system and to prevent upward movement of uidV when pressure exists in the system. The upper end of the reservoir is normally closed by a screw threaded filler cap 25e. While bleeder plugs 24 and replenishing reservoirs 25 are shown applied to the devices B, the master cylinders I2 and the manifold I6 it should be understood that such elements may be placed at all points in the system corresponding to the highest levels of the respective several separate bodies of uld.

It should be apparent that, if desired, a single master cylinder I2 may be used in conjunction with the manifold I6 and the devices B associated with the respective tubes I1. Also the number of devices B associated with the tubes I1 may be reduced to two and two tubes I1 may be connected to each of these devices B. The devices B associated with a tube I1 may of course be used to connect together sections of that tube I1 instead of being connected between the tube I1 and the manifold I6.

Various embodiments of the inventive idea of my fluid sectionalizing device B may be constructed and one such embodiment is shown in Fig. 4'. 'Ihis embodiment includes a cylinder 23 having an integral cylinder head 28a closing one end thereof and a removable cylinder head 21 closing the other end thereof and secured to the tion 25h of the stem 25a a check valve is pro-A cylinder 26 by means of screws 28. The cylinder heads 26a and 21 are respectively provided with outwardly projecting connection elements 29 and 30 each communicating with the interior of the cylinder 26. Within the cylinder is a piston 3I having flanged sealing elements 32 secured to the respective ends thereof by means of washers 33 and screws 34 and with the flanges of the sealing elements 32 projecting outwardly of the ends of the piston 3|. The heads of the respective screws 34 comprise abutment elements and for cooperation therewith the inner sides of the cylinder heads 26a and 21 are respectively provided with centrally located inwardly projecting integral bosses 26h and 21a. A helical compression spring 35 vis interposed between the piston 3| and the removable cylinder head 21 and the end turns at the respective ends of the spring 35 encircle and are h'eld in positionby the head of one of the bolts 34 and the boss 21a. A bleeder plug 24 is provided in the upper portion of the cylinder head 26a and a replenishing reservoir 25, such as previously described, is provided at the upper side of the cylinder 26. 'I'his embodiment of my fluid sectionalizing device may be used in a hydraulic brake operating system in the same manner as the first described-device B. 'I'he connection element 29 is connected to a source of fluid under pressure and the connection element 3.0 is

It is apparent that I have invented a novel,

eilicient, simple and reliable hydraulic brake operating system wherein leakage of .fluid in one portion of the system does not render the entire system inoperative.

It will, of course, be understood that various changes may be made in the form, details, proportions and arrangement of the parts without departing from the scope of my invention, which,

generally stated, consists in a device capable of f carrying out the objects above set forth and in the novel parts and combinations of parts disclosed and defined in the appended claims.

What is claimed isz- 1. Fluid sectionalizing means for a hydraulic brake operating system comprising a chamber, a fluid-tight diaphragm mounted within said chamber to divide said chamber into two portions, one of said portions having communication with the fluid pressure exerting means of said system and the other of said portions having communication with a fluid pressure actuated brake operating means of said system, and a backing member mounted in said chamber for said diaphragm to lie against when said diaphragm ROLLAND C. SABINE. 

